Air deflector for drying ovens



Jan. 16, 1968 w. B. HARRISON ET AL 33 3 AIR DEFLECTOR FOR DRYING OVENSFiled Oct. 24, 1965 p .v. O

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WILLIAM RAYMOND United States Patent 3,363,327 AIR DEFLECTOR FOR DRYINGOVENS William B. Harrison, Dedham, and Raymond E. Price,

Belmont, Mass., assignors to W. R. Grace & Co., Cambridge, Mass., acorporation of Connecticut Filed Oct. 24, 1965, Ser'. No. 504,393 2Claims. (Cl. 34-105) This invention relates to drying ovens forcontainer closures and particulary to an air deflector for such ovenswhich prevents closures entering and leaving the oven from beingdisplaced.

Container closures are provided with gaskets by flowing a liquidcomposition onto the panel around the internal periphery of the closure,and, in the case of bottle crowns, over the whole internal surface.Subsequently, the suspending medium, if the composition is a dispersionor a solvent solution, must be removed. If the composition is aplastisol, then the lining must be brought up to that temperature atwhich the suspending plasticizer solvates the dispersed resin. Both ofthese operations take place in so-called ovens.

Container closure lining ovens are quite large, and usually are equippedwith an open mesh transport belt on which ranks of closures, inner sideup, are placed after the liquid composition has been placed in theclosure by the lining machine. The belt, which moves constantly, runsfrom end to end of the oven. In the most common types of ovens, heat issupplied by a gas furnace. The heated air is driven, usually downwardly,onto the closures and passes through the mesh belt to an exit ductwhence it is recirculated through the furnace and the oven by a powerfulfan. Necessarily, in such a system, the combustion products vent and,although the ovens are designed for substantial recirculation of theheated air, air leakage occurs inwardly at the entrance of the oven andoutwardly at the oven exit.

In the case of plastisol linings, at the moment that the lining reachesfluxing temperature, the lining is a viscous liquid which will flow outof position should the closure not lie horizontally on the belt. If theclosure is cocked, the liquid will flow to the lowermost point, anduneven gaskets will be produced.

It has been determined that the cocking or tilting of the closures onthe carrier belt is caused not so much by misadjustments of the transfermechanism but by air which may lift and tilt the closures as they enteror leave the oven. This effect is characteristic of closures formed oflightweight metals, such as aluminum.

Considering the entrance end of the oven, closures pass into it througha slot which extends across the full width of the transport belt, and iswide enough to provide ample vertical clearance for the closure. The aircurrents within the oven flow down its vertical face and also move in ahorizontal direction' The result of this mixed flow is an upward thrustwhich frequently tilts the closure to some position from its normalhorizontal plane.

At the exit end of the oven, air flow' conditions are reversed. There isalso a tilting and lifting component, for the air cannot only move outhoriozntally, but moves upwardly as it escapes through the slot. Cookingof closures can occur at this position also, and since the closures arehot and their linings are liquid (in the case of plastisols), unevengaskets will be produced. Presupposing that solvent or waterbased linedclosures have entered and travelled through the oven in a horizontalposition, cocking at the exit, when solvent or water-based sealingcompositions form the gasket body, does not cause trouble since thegasket, by the time it has reached the exit position, has become a solidsubstance.

It has been discovered that if a deflector plate is installed both atthe entrance and exit end of the oven and "ice is so shaped as to causea substantial component of the airflow pattern to be directed downwardvertically that displacement by air of the closure does not occur.

This invention may best be understood by reference to the drawings inwhich FIG. 1 is a perspective View of a deflector plate mounted to theentrance end of an oven.

FIG. 2 diagrammatically illustrates a sectional view of closures movingthrough a drying oven and shows the characteristic airflow patterns.

Referring to FIG. 1, a deflector, shown generally at 10 is mounted tothe entrance end of oven 5 and is substantially the same at both theentrance and at the exit of the oven. The deflector comprises an angularbent sheet of metal having a vertical portion 11 which is secured to theend wall of the oven by suitable means, such as rivets 12. An upwardlydirected angular portion 13 departs from the lower end of the verticalportion substantially at an angle of 45. A longer, downwardly directedangular portion 14 extends from the upper margin of portion 13 and liesat an angle of to the portion 13. At the point 15, downwardly directedportion 14 merges into a horizontal portion 16.

FIG. 2 shows a deflector supported from each of the outside walls 17 and18 of the entrance and exit ends respectively of the oven. They arepositioned so that the horiozntal portion 16 lies above the moving belt19 which passes through the oven.

When the fan (not shown) is started and deflectors are not used, leakageof air out of the entrance slot 23 from the oven as a result of the downdraft established by the fan and reaction from the floor of the ovencauses an upward air flow component which can displace a closure 20placed on the open mesh transport belt 19. When the deflector is inplace, the airflow pattern follows substantially the path of the arrowsshown in FIGURE 2. A substantial amount of the outflowing air isintercepted by the downwardly directed surface 14 with the result that adownward vertical component indicated at 21 is given to the airflow anda downwardly directed pressure is exerted on the panel surface of theclosure 20 which successfully holds the closure in a horizontalposition.

In the case of the exit end of the oven with no deflector, the airleaking out of the oven has an upward component which results not onlyfrom the air being diverted upward from the floor of the oven, but fromits expansion into the lower pressure air in the room. Accordingly, aclosure 20a, occupying a position at the exit could be lifted andtilted.

When the deflector 10 is fastened to the end wall 18 of the exit end ofthe oven, the airflow pattern follows substantially that shown by thearrows. A substantial amount of flow toward the exit is made laminar bythe action of the horizontal portion 16. The upper portion of thislaminar flow is intercepted by the downward ly directed portion 14 withthe result that a vertical component shown at 22 which exertsconsiderable force, exists and is directed on to the panel of a closure2011. This force is suflicient to prevent any displacement of a closureas it passes out of the oven.

The dimensions of the air-stabilizing deflector necessarily depend uponthe width of the entrance and exit passages, and will be proportioned tooven size. But as an example, it has been found in ovens which have anentrance and exit vertical dimension of 2" above the belt, the point 15(the lowermost extent of the deflector plate) should be placedapproximately 1" below the end wall and extended into and away from theoven approximately 4".

The improvement substantially eliminates uneven linings caused by thetilting of the closure and has proved 3 particularly valuable in thefluxing or drying of linings on closures which are provided with pulltabs. Such closures are inherently less stable than closures of con-Ventional design.

We claim:

1. In an oven adapted to heat container closures having an open meshendless-belt transport means, end Walls and entrance and exit slotopenings in said end Walls, and where in said oven a forced aircirculation is maintained, means to cause air entering and escaping fromsaid oven through said slots to exert a vertically directed downwardforce upon closures occupying positions on said belt comprising airdeflectors aflixed to the end walls of said oven transverse to said beltcomprising a plate having an airflow directing portion angularly and anairflow stabilizing portion horizontally disposed relative to said belt,the lower margin of said angular portion being positioned below theupper margin of said entrance and exit slots to intercept a portion ofthe flow of air entering and leaving the oven, the said air interceptingportion lying at such an angle that the said air flow will be divertedsubstantially downwardly to exert a direct downward force upon closuresdisposed upon said belt, thereby preventing displacement of the closureby entering or escaping air.

2. In an oven, means according to claim 1 comprising airflow deflectorshaving the said airflow stabilizing portions directed outwardly from theentrance and exit ends of said oven.

References Cited UNITED STATES PATENTS 2,647,811 4/1954 Thornburg 34216X 2,985,437 5/1961 Sargeant 34242 X 3,096,162 {7/1963 Jepson 34-33FREDERICK L. MATTESON, JR., Primary Examiner. I

E. G. FAVORS, Assistant Examiner.

1. IN AN OVEN ADAPTED TO HEAT CONTAINER CLOSURES HAVING AN OPEN MESHENDLESS-BELT TRANSPORT MEANS, END WALLS AND ENTRANCE AND EXIT SLOTOPENINGS IN SAID END WALLS, AND WHERE IN SAID OVEN A FORCED AIRCIRCULATION IS MAINTAINED, MEANS TO CAUSE AIR ENTERING AND ESCAPING FROMSAID OVEN THROUGH SAID SLOTS TO EXERT A VERTICALLY DIRECTED DOWNWARDFORCE UPON CLOSURES OCCUPYING POSITIONS ON SAID BELT COMPRISING AIRDEFLECTORS AFFIXED TO THE END WALLS OF SAID OVEN TRANSVERSE TO SAID BELTCOMPRISING A PLATE HAVING AN AIRFLOW DIRECTING PORTION ANGULARLY AND ANAIRFLOW STABILIZING PORTION HORIZONTALLY DISPOSED RELATIVE TO SAID BELT,THE LOWER MARGIN OR SAIID ANGULAR PORTION BEING POSITIONED BELOW THEUPPER MARGIN OF SAID ENTRANCE AND EXIT SLOTS TO INTERCEPT A PORTION OFTHE FLOW OF AIR ENTERING AND LEAVING THE OVEN, THE SAID AIR INTERCEPTINGPORTION LYING AT SUCH AN ANGLE THAT THE SAID AIR FLOW WILL BE DIVERTEDSUBSTANTIALLY DOWNWARDLY TO EXERT A DIRECT DOWNWARD FORCE UPON CLOSURESDISPOSED UPON SAID BELT, THEREBY PREVENTING DISPLACEMENT OF THE CLOSUREBY ENTERING OR ESCAPING AIR.